The amount of data transmitted over the internet has been growing exponentially. With the rapid development of the technology, wireless connections will not only connect people via voice and data communications but also will connect smart devices, also called Internet of Things (IoT). The number of devices connected through wireless communication demands higher efficiency of the wireless network. Many wireless technologies are not currently adapted to support the emerging market of IoT. For example, the WiFi network, widely used today, is not suitable for such development because the current WiFi is designed to offer higher throughput to a limited number of wireless communications devices concurrently. The current WiFi network uses single user (SU) mode when accessing the network. In a high-density environment, the single-user mode causes many collisions, reduces the total network throughput, and possibly leads to congestive collapse.
In the tradition WiFi network, SU uplink transmission is used. During SU uplink, the WiFi radio holds back and only transmits for one user at a time. The inefficiency of single-user uplink requires many retransmissions due to collisions. Further, in a high-density network, especially with many IoT devices, the majority of data packets are control and management frames.
Multiple user (MU) uplink method reduces collision and therefore, increases overall system efficiency. The problem remains how to implement multi-user uplink access. For example, overlapping base station (OBSS) exists in typical deployments. Inter BSS interferences exist caused by OBSS.
Improvement and enhancement are required for uplink MU OFDMA/MIMO protocol.